Field of Invention
The present invention relates to the field of camera module, and more particularly to a single and/or array camera module with circuit board unit and photosensitive unit and the manufacturing method thereof
Description of Related Arts
COB (Chip On Board, chip packaging) technique is a very important technical process in the process of assembling and producing camera module. A camera module produced by means of the conventional COB technique is assembled of a circuit board, a photosensitive sensor, a lens holder, a motor drive, and a camera lens.
FIG. 1 refers to a perspective view of a camera module produced by means of the conventional COB technique. The camera module includes a circuit board 1P, a sensor 2P such as a photosensitive chip, a lens holder 3P, an optical filter 4P, a motor 5P, and a camera lens 6P. The sensor 2P is installed on the circuit board 1P. The optical filter 4P is installed on the lens holder 3P. The camera lens 6P is installed on the motor 5P. The motor 5P is installed on the lens holder 3P, so that the camera lens 6P is positioned along a photosensitive path of the sensor 2P.
It is worth mentioning that there is often a plurality of circuit components 7P, such as resistors, capacitors, and etc., installed on the circuit board 1P. These circuit components 7P protrude from the surface of the circuit board 1P. However, the lens holder 3P has to be mounted on the circuit board 1P with the circuit components 7P. According to the conventional COB technology, there are disadvantages in the assembling and coordination relationships among the circuit board 1P, the circuit components 7P, and the lens holder 3P, which also restrict the development for the camera module to become lighter and thinner.
It is also worth mentioning that the sensor 2P is usually electrically connected with the circuit board 1P with conductive elements such as gold wires 8P for data transmission between the sensor 2P and the circuit board 1P. Based on the feature and structure of the gold wires 8P, the gold wires 8P are usually curvedly bent and protruded from the surface of the circuit board 1P. Therefore, the assembling process of the sensor 2P, like the circuit components 7P, has the similar adverse effects to the camera module.
In particular, firstly, the circuit components 7P and the gold wires 8P are directly exposed on the surface of the circuit board 1P. As a result, they will inevitably be affected during the subsequent assembling processes, such as adhering the lens holder 3P, soldering the motor 5P, and etc., wherein solder resists, dusts and etc. during the soldering process may easily stick to the circuit components 7P. Besides, because the circuit components 7P and the sensor 2P are connected and provided in a common space, those dusts and pollutants can easily and adversely affect the sensor 2P that can result in undesirable occurrences such as dark spots of the assembled camera module, which increases the defective rate of the camera module.
Secondly, the conventional lens holder 3P is positioned at the outer side around the circuit components 7P. Therefore, to mount the lens holder 3P on the circuit board 1P, a safe distance is required to be reserved between the lens holder 3P and the circuit components 7P in both horizontal direction and upward direction, that results in increasing the thickness of the camera module and the difficulty to the thickness reduction of the camera model.
Thirdly, during the COB assembling process, the lens holder 3P or the motor 5P is adhered on the circuit board 1P with adhesive material, such as glue. During the adhering, an Active Arrangement (AA) technique is usually required to adjust the central axis lines of the sensor 2P and the camera lens 6P being aligned coincidently in both horizontal and vertical directions. Therefore, in order to satisfy the practice of the AA technique, it is required to additionally provide more glue between the lens holder 3P and the circuit board 1P as well as between the lens holder and the motor 5P, so as to reserve adjustment space between each other. Nevertheless, this adjustment space requirement will not only further increase the thickness of the camera module, rendering it substantially being more difficult to reduce the thickness of the camera module, but also cause tilt discrepancy of the assembling more easily during such multiple adhering process. Moreover, it further requires a higher evenness for the lens holder 3P, circuit board 1P and motor 5P.
In addition, in the conventional COB technology, the circuit board 1P forms the basic affixing and supporting body for the camera module, so that the circuit board 1P is required to have a predetermined structural strength. This requirement makes the circuit board 1P having a larger thickness, which also increases the thickness of the camera module from another aspect.
Along with the development of all kinds of electronic product and smart device, camera modules are also developed to achieve higher performance and more compact size. Meanwhile, in order to meet the various requirements of high performance development, including high resolution and high image quality, more and more electronic components are provided in the circuit, the size and surface area of the sensor becomes larger and larger, and the passive components, such as driving resistors and capacitors, are correspondingly increased. As a result, the size of the electronic device becomes larger and larger, the assemble difficulty thereof increases accordingly, and the overall size of the camera module becomes bigger and bigger. In view of the above factors, the conventional assembling method of the lens holder, circuit board, and circuit components becomes a great restriction, to a certain extent, to the development of a lighter and thinner camera module.
Referring to FIG. 29, a sectional perspective view of an array (twin-lens) camera module assembled by the above conventional COB assembling method is illustrated.
Currently, most electronic products tend to have more functions integrated, that creates more and more cross-categorical products. For example, cellular phones have been transformed from communication devices to highly integrated mobile electronic devices that integrally achieve the diverse and multi-dimensional functions of communication, photography, internet accessing, navigation, and etc.
However, the camera module installed in the current mobile electronic devices is usually a single lens camera module that can no longer satisfy the user's multi-functional application demand of the mobile electronic device in both image quality and effects of photography.
Accordingly, camera module with more than one lens, for example array camera module such as twin-lens camera module, is provided to produce shooting modes that imitate the arrangement of the two eyes of a human being. Moreover, such twin-lens camera module provides better performances than the single lens camera module in 3D photographing and scanning, gesture position recognition, naturalness of color, auto-focusing, panoramic and deep photography, bokeh photography, and etc. Therefore, it will be an important direction of development in the camera module industry to have camera module with more than one camera lens. When a twin-lens camera module is capturing images, it utilizes two imaging modules that are different in spatial positions to respectively capture images from two positions. Then the images respectively captured by these two imaging modules are synthesized according to an image synthesis process, so as to bring a final image of the multi-lens camera module. It is understandable that, in this process, the consistency of the image effect of the resolution, the shading, the color, and etc. of each camera module of the multi-lens camera module and the deviances in the horizontal, vertical and longitudinal directions are important factors to judge the image quality of the twin-lens camera module.
However, currently, the structure and technology of manufacturing and assembling the twin-lens camera module are far away from ensuring the image quality of the twin-lens camera module as demanded. FIG. 29 illustrates a twin-lens camera module made by the conventional assembling method, which includes a circuit board 10P, two lens holders 20P, and two imaging modules 30P, wherein each of the imaging modules 30P includes a motor-camera lens unit 31P. The lens holder 20P is independently arranged at the same side of the circuit board 10P and connected with the other lens holder 20P by means of the circuit board 10P. The motor-camera lens units 31P are arranged on the lens holders 20P respectively so as to be supported by the lens holders 20P respectively. It is understandable that, according to the conventional assembly technology for the twin-lens camera module, since each lens holder 20P is independently adhered on the circuit board 10P, it is really difficult to control the dimensions, positions and etc. between the lens holders 20P. As a consequence, the consistency of the parameters, such as the dimensions and positions between the frames of the twin-lens camera modules, is poor. In view of the structure of the conventional twin-lens camera module, each lens holder 20P is independent by itself and merely connected to the circuit board 10P. Nonetheless, the circuit board 10P is usually a PCB, printed circuit board, which is relatively soft and easy to be distorted, that it is difficult to ensure the overall rigidity of the conventional twin-lens camera module. In addition, during the usage after the twin-lens camera module is assembled, such independent structure can easily cause high positioning tolerance and instability of the relative dimensions among the elements, such as the motor-camera lens units 31P, of the imaging module 30P. Moreover, other problems, like the photosensitive axis of the imaging module 30P easily deviating from the designated position, may easily happen. Once any of these situation occurs, the image quality of the twin-lens camera module will be adversely affected. For example, there are uncontrolled factors or bigger adverse impacts to the final imaging effect of the image synthesis.
Besides, the assembling of the multi-lens camera module is based on the conventional Chip On Board (COB) technology, wherein there are usually protruded circuit components 11P on the circuit board 10P. The circuit board 10P also comprises a photosensitive element such as a sensor 12P mounted thereon. The sensor 12P is usually connected to the circuit board 10P with conductive elements such as gold wires 121P which are normally curvedly protruded from the circuit board 10P. As a result, these protruding circuit components 11P and gold wires 121P also cause certain disadvantageous factors to the assembling of the camera module.
The circuit components 11P and the gold wires 121P are directly exposed on the surface of the circuit board 10P. Accordingly, they inevitably affect the subsequent assembling processes, such as the adhering the lens holders 20P, soldering the motor-camera lens units 31P, and etc., wherein solder resist, dust and etc. from the soldering process can easily stick on the circuit component s11P. Besides, because the circuit components 11P and the sensors 12P are disposed in a common space, the dusts and pollutants can easily affect the sensors 12P and such influences can result in undesirable occurrences such as dark spots of the assembled camera module that decreases the product yield rate.
In addition, the lens holders 20P are positioned at the outer side of the circuit components 11P. Therefore, to adhere the lens holders 20P on the circuit board 10P, a predetermined safety distance must be reserved among the lens holders 20P and the circuit components 11P in both horizontal direction and upward direction, that substantially increases the thickness of the twin-lens camera module and the difficulty to reduce the thickness of the twin-lens camera model.
Besides, comparing to the single-lens camera module, the multi-lens camera module relates to issues of coordination between multiple camera modules. The photosensitive axises among all camera lenses are required to be consistent. However, the consistency of the photosensitive axes of multiple camera lens modules based on the traditional COB technology is hard to be ensured. Furthermore, the overall size of a conventional multi-lens camera module is larger, which is more sensitive to the strength and smoothness of the circuit board and, therefore, the circuit board is thicker.